Anther development, pollen germination rate, and expression of anther and pollen development-related genes in ‘DK’, ‘ZY’, and ‘Tub’. (a) Anther development and dehiscence in ‘DK’. T1-T5 are consistent with FlT1-FlT5, and T6 represents 12 hours after blooming. (b) Anther development in ‘Tub’. T1-T5 are consistent with FlT1-FlT5, and T6 represents 12 hours after blooming. (c) Pollen germination rate of ‘Tub’, ‘ZY’, and ‘DK’. ****P-value <0.0001, t-test, n = 10. (d) Expression (FPKM) of anther and pollen development-related genes in ‘DK’, ‘ZY’, and ‘Tub’ from flowers at different stages, including FlT1, FlT2, FlT3, FlT4, and FlT5.
Wax apple (Syzygium samarangense), known for its crisp texture, rose-like aroma, and health benefits, faces breeding challenges due to its complex genetic diversity and limited genomic data. These obstacles have hindered efforts to improve key fruit qualities such as size and sugar content. Addressing these issues requires comprehensive genomic research to unravel the genetic mechanisms underlying these traits.
Led by scientists from the Fujian Academy of Agricultural Sciences and Fujian Agriculture and Forestry University, this study (DOI: 10.1093/hr/uhad214) was published on October 25, 2023, in Horticulture Research. The research provides chromosome-scale genome and transcriptome data of the wax apple, focusing on genes that regulate fruit size, sugar metabolism, and male sterility. This pioneering work opens new possibilities for the molecular breeding of wax apple varieties with enhanced fruit characteristics.
The study assembled a 1.59 Gb genome, revealing three rounds of whole-genome duplication events in wax apple. Key genes influencing fruit size, including APETALA1 (AP1) and APETALA1 (AP2), were identified, which promote growth by regulating sepal development. For sugar content, elevated expression of sugar transporter genes such as Sugars Will Eventually be Exported Transporters (SWEETS) and Sucrose Transporters (SUTs) was linked to sweeter fruit varieties. Moreover, the research discovered that male sterility in certain varieties results from reduced expression of critical genes like DYSFUNCTIONAL TAPETUM1 (DYT1), TAPETUM DEVELOPMENT AND FUNCTION1 (TDF1), and ABORTED MICROSPORE (AMS), which are essential for tapetum development and pollen viability. This male sterility contributes to the formation of seedless fruits, a highly valued trait in the market.
“This research represents a major advance in understanding the genetic foundations of essential traits in wax apple,” said Dr. Lihui Zeng, a co-author of the study. “The haplotype-resolved genome serves as a crucial resource for exploring genetic diversity and selective breeding, bringing us closer to creating superior wax apple varieties with improved size, sweetness, and seedlessness.”
The insights gained from this study are expected to accelerate breeding programs focused on developing wax apples with enhanced fruit size, higher sugar content, and seedless traits, aligning with consumer demands. The findings also provide a valuable framework for improving other fruit crops facing similar breeding challenges, marking a significant step forward in the field of horticultural genomics.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhad214
Funding information
This work was supported by the Natural Science Foundation of Fujian Province (2020 J011361), and the High-quality Development beyond the ‘5511’ Collaborative Innovation Project in Fujian Province (XTCXGC2021016-4).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number two in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.
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